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Scientists in the United States have created a tiny antenna capable of receiving any radio signal, based on the human ear.

The new universal radio could lead to better reception and a new class of electronics that can pick up any radio frequency.

"The human ear is a very good spectrum analyser," says Rahul Sarpekhkar, a professor at MIT who co-authored the paper in the June issue of the IEEE Journal of Solid-State Circuits. "We copied some of the tricks the ear does, and mapped those onto electronics."

The unique architecture of the human ear allows it to detect a wide range of sounds. A spiral with thousands of tiny hairs, called cilia, of different sizes help the ear to separate out each frequency, from 100 hertz up to 10,000 hertz, and transmit that information to the brain.

To detect electromagnetic waves instead of pressure waves the MIT scientists used circuits, in place of cilia. Starting on the outside edge of the 1.5 by 3 millimetre chip are tiny squares, each one corresponding to a different size radio wave.

As they spiral into the centre, the squares become larger and larger. The outer spiral detects the highest energy, shortest frequency waves, while the centre circuits detect less energetic, longer frequency waves.

The universal radio might be inspired by the human ear, but in terms of spectrum range that can be detected, the electromagnetic ear outperforms the human by about a million to one.

The electromagnetic ear detects this huge range of frequencies using the same amount of energy that a typical mobile phone does.

Multiuse device

Other devices that can examine a range of radio frequencies currently exist, but they require much more power.

The low power usage of the electromagnetic ear means it would be ideal for portable electronic devices.

The MIT team has a patent on their chip, but so far doesn't have firm plans to commercialise the technology.

The first use of a universal radio, say the scientists would be to eliminate any noise in the signal.

For example, if the signal received by a mobile phone is breaking up, the chip could switch to a nearby and less cluttered frequency. Other uses for the technology could include television receivers, wireless internet connections and GPS devices.

In the future, a mobile phone equipped with such a chip could receive TV programs, songs on the radio and other radio transmissions.

While a chip that can receive virtually any radio signal is good, a device that can also transmit on any frequency would be even better.

Adding more power to the device can achieve this, and the MIT scientists are still working on it, but for now, creating a universal radio that receive any signal is still impressive.